Both psk3 entries run the same demodulation as the psk2 entry beside them and
differ only in the constant given to test(). test() accepts a word only when
that word's own modulation field matches the constant, so the psk3 entry needs
a recovered word whose field reads 3.
Field 3 is 00011, so it needs two adjacent 1's. What this demodulation recovers
is the data's rising edges, and a rising edge needs a 0 before the 1, so no two
of them are ever adjacent. The words it produces can never carry field 3, and so
the psk3 entries can never match the case they were written for.
What they can do, however, is match on a demodulation error, and then detect
names psk3 and a block 0 word the tag does not hold.
psk3 is still reached, by ruling psk2 out from the broadcast period rather
than by demodulating for it - see t55xx_psk3_resolve().
Tags that only these branches matched now read as psk2, or as undetected
where no offset yields a plausible psk2 word, on the basis that a wrong
answer is worse than none if nothing about it tells you it is wrong.
Edited by a human.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The client demodulates psk2 and psk3 the same way, and against a psk3 tag
that demodulation keeps only the leading bit of every run of ones. A psk3
config word therefore always reads back as its psk2 neighbour, one bit out,
and detect structurally cannot tell the two apart from the waveform alone.
It said psk2 anyway. Worse, the data-block probe meant to settle it
confidently answered psk3 even for a freshly wiped psk2 tag, where a page
of zeroes has no adjacent ones under either modulation.
Report what is actually known:
- print "PSK2 or PSK3 ( ambiguous )" when the read fits both
- list the words block 0 could be, rather than printing one and relegating
the rest to a note
- weight the probe's evidence, so empty blocks settle nothing
- narrow that list with things the tag cannot hide - the subcarrier it
transmits on, and how many blocks it broadcasts, which constrains MAXBLK and
also rules out the sequence terminator
Where that leaves one word, block 0 reports it. Where it does not, detect
says so rather than choosing.
Edited by a human.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
100 array declarations uint8_t x[PM3_CMD_DATA_SIZE]
21 receive sites — GetFromDevice, APDU/smartcard response buffers
All in a days work
Signed-off-by: Niel Nielsen <nieldk@gmail.com>
PM3_CMD_DATA_SIZE went 512 -> 624 without a capabilities bump, so a new
client connects to old firmware and every oversized command dies at the
device's length check with no message.
Append max_cmd_data_size, bump to v9. The client now accepts an older
capabilities struct - it only ever grows by appending, so an older layout
is a prefix - and defaults the frame size for pre-v9 firmware.
SendCommandNG bounds by the device value instead of the compile time one.
Also zero init capabilities_t on the device, it leaked stack bytes.
Allocate EF_SOD parsing scratch buffers on the heap so macOS worker threads do not exceed their stack while reading protected travel documents.
Co-Authored-By: Codex <noreply@openai.com>
Niel Nielsen